Have you already tried a normal shutdown and restart of Windows to try to free up file locks?

After that, if problems continue, could you let us know what you get when you run the "Verify Integrity" function. That's here:

Open Firefox's Troubleshooting Information page using any of these methods:

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

Near the bottom, there is a section titled Places Database -- that's the file which stores history and bookmarks. Click the button labeled Verify Integrity. There may be a 10-15 second delay before results appear.

If all is well, the report that appears below the button should start with:

> Task: checkIntegrity
+ The places.sqlite database is sane
+ The favicons.sqlite database is sane

Does yours say that, or something else? You can select and copy the report, and then paste it into a reply for review and comment.

Thank you for your reply.

I did restart the computer and the problem was not solved.

I took the steps you listed and got this response when I clicked "Verify integrity":

> Task: checkIntegrity + The places.sqlite database is sane + The favicons.sqlite database is sane > Task: invalidateCaches - Unable to invalidate caches > Task: checkCoherence - The task queue was cleared by an error in another task. > Task: expire - The task queue was cleared by an error in another task. > Task: originFrecencyStats - The task queue was cleared by an error in another task. > Task: vacuum - The task queue was cleared by an error in another task. > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task.

It might be necessary to remove the Places database, but as a starting point, perhaps it would help to remove two temporary files. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" Help > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > Exit
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then if you find these two files, delete them and start Firefox again to see whether it helps:

• places.sqlite-shm
• places.sqlite-wal

If you run Verify Integrity after that, does it get further in the process?

If those files do not exist or removing them does not help:

You can rename the Places database and see whether that resolves the issue (again, while Firefox is not running):

Right-click places.sqlite, click Rename, then add OLD so the name is placesOLD.sqlite

Firefox should start up with no browsing/download history, but should rebuild bookmarks from one of the automatic backup files. Did that work?

I greatly appreciate your help. I've tried to faithfully follow your instructions. Unfortunately, the problem still remains.

1. I still get the following when I first load Firefox: “The bookmarks and history system will not be functional because one of Firefox’s files is in use by another application. Some security software can cause this problem.” I should note that I use McAfee and have been using DuckDuckGo as my search program.

2. When I try to add a bookmark using the star in the URL box I get no response.

3. I still cannot get the backup file to work. When I try to restore from a backup file (I’ve tried various ones with different dates) I always get this message: “Unable to process the backup file.”

4. After it took the various steps you recommended (including renaming the places.sqlite file) I reran the Verify Integrity for the Places database and still got this:

> Task: checkIntegrity + The places.sqlite database is sane + The favicons.sqlite database is sane > Task: invalidateCaches - Unable to invalidate caches > Task: checkCoherence - The task queue was cleared by an error in another task. > Task: expire - The task queue was cleared by an error in another task. > Task: originFrecencyStats - The task queue was cleared by an error in another task. > Task: vacuum - The task queue was cleared by an error in another task. > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task.

I would appreciate any advice you might have.

1. I still get the following when I first load Firefox: “The bookmarks and history system will not be functional because one of Firefox’s files is in use by another application. Some security software can cause this problem.”

Sorry, I missed that before. The other file you might rename is the icons file, favicons.sqlite (this article mentions deleting them, but I generally prefer to rename just in case one needs to roll back the change): Fix "The bookmarks and history system will not be functional" error message.

Thank you very much for your help. Your recommendation solved the problem. I